Means for carrying off heat generated in electrical apparatus



Jul 1 1924.

G. SCHROEDER MEANS FOR CARRYING OFF HEAT GENERATED IN ELECTRICAL APPARATUS Filed July 1 1924.

G. SCHROEDER MEANS FOR CARRYING OFF HEAT GENERATED IN ELECTRICAL APPARATUS Filed March 11.

1921 2 Sheets-Sheet 2 Fig. 4..

Patented July 1, 1924.

UNITED STATES GIULIO SCI-IROEDER, OF HALE, ENGIIAND.

MEANS FOR CARRYING OFF HEAT GENERATED IN ELECTRICAL APPARATUS.

Application filed March 11, 1921.

To all whom it may concern:

Be it known that I, GIULIO SGHROEDER, a subject of the King of Italy, residing in Hale, Cheshire, England, have invented certain new and useful Improvements in Means for Carrying Off Heat Generated in Electrical Apparatus, of which the following is a specification.

This invention relates to the'cooling of electric apparatus by removing heat from cores which are the seat of fluxes which undergo relatively rapid changes either in quantity or position. It deals particularly with alternating current dynamo-electric machines.

In the method of working dealt with in this invention cooling is effected by means of liquid flowing through ducts in the core which are disposed across the path of movement of the lines of flux.

This movement of the flux will accordingly tend to produce a difference of electric potential between the two ends of a duct and between the differently placed ducts in the core. the practical application of this method of cooling to provide that the possibility of this potential difference becoming effective in producing current in the duct system shall be reduced to a minimum.

In accordance with the present invention this result is attained by so forming and interconnecting the ducts that the paths in which the currents would tend to flow are of non-conducting or very poorly conducting material. In general this method of arranging the circulating system has two limiting forms; in one of them the whole of the circulating system within the apparatus is made of insulating material; in the other form the system is constructed mainly of metal with insulating insertion pieces arranged to prevent the completion of circuits round which would act the electro-motive forces due to the flux movement. Between these two extreme forms of construction a number of intermediate stages exist.

Examples of these arrangements will be described with the aid of the accompanying drawings in which Figure 1 shows a stator of an electrical machine such as a turboalternator, the upper part being a longitudinal section showing an arrangement in which longitudinal tubes through the core connect with chambers mounted on the clamping rings. Figure 2 shows a partial It is therefore of importance in Serial No. 451,628.

end view of a similar machine having applied to it an arrangement of a type in which a cast metal chamber is arranged in connection with tubes made of insulating material and divided so as to cause the liquid to pass backwards and forwards through the core. The casting may either serve as the clampmg ring or be carried by it. Figure 2 also shows a partial end view of a similar machine having applied to it an arrangement of a type in which metallic tubes are inserted in the core and are interconnected at the ends by insulating couplings. Figures 3, 4 and 5 show in detail forms of insulating couplings applicable to various cases.

The ducts will in general be formed by means of a series of registering holes in the laminations a, tubular bridge pieces 5 being inserted where these longitudinal ducts cross any radial ducts c that may be provided.

In general it will be necessary to line or coat the inside surface of the duets with a material that shall prevent the escape of the liquid and which may also be required to prevent the liquid from having a corrosive action on the core.

lVhere a non-conducting coating is to be applied to the ducts the application can conveniently be made by spraying the material in a liquid or semi-liquid form on to the Wall of the duct or by first applying a liquid or semi-liquid coating and then distributing powdered material over the surface before it is dry so as to build up a coating. The spraying method would for instance be used with a solution of celluloid or other material which is capable of forming a non-conducting and resistant coating.

In place of a coating applied by spraying, material which can be vulcanized in position may be employed and this will be inserted in the form of a strip or sheet; for instance, a niandril slightly sma-llenthan the duct may be wrapped round with a strip or sheet formed from a rubber and sulphur mixture and this covered mandril may then be inserted into the duct and can then be heated, for instance, by the passage of steam through it for the purpose of vulcanizing the coating which, in the process of vulcanization will expand slightly and adhere to the wall of the duct after which the mandril may be withdrawn. In order to permit this withdrawal, known precautions must be taken to prevent the coating from adhering to the mandril. For a coating of this kind a mixture is preferably employed which on vulcanization produces ebonite or hard rubber, and in order to reduce the time of curing, an accelerator is preferably included in the mixture.

.In another method of application 1n which a metallic lining is provided, this may be inserted in the form of a tube fitting approximately the inside of the duct and side of the duct is preferably coated with some insulating material such, for instance, as is employed between th laminatlons.

In the arrangement shown in Figure i one of the end chambers (Z serves for the inflow of the cooling liquid while the other of such chambers serves for the outflow. These chambers may either be formed as complete rings or may be divided into segments, the

segments round a circle being'for instance alternately inlet and outletchambers so as to obtain an approximation to equalization of temperature throughout the length of the core. The tubes 6 may either be of insulating material or of conducting material. In the former case, they may be for instance made of hard rubber or ebonite having embedded in or attached to their ends suitable metallic ferrules for attachment to the plates 7' which form the inner walls of the chambers dr Vhere the tubes 6 are of conducting material they will be provided with insulating arrangements at their ends, for instance of the type indicated in Figure 3. In that arrangement the end of the tube is fitted with an insulating bush 9 which is encircled by a metal bush h which is split longitudinally and has a conical outer fac which fits within the correspondingly shaped end of the screwed ferrule 7 which fits in a threadedhole in the plate 7. As will be seen from Figure 3 the split bush it lies at its inner end against the clamping ring'y' so that when the ferrule is screwed, in, thebush is compressed andcaused to force the insulating bush 9 into contact with the tube 6 making a; tight joint.

The outer part of ,each chamber (Z may be secured to the plate f by bolts inserted at the points indicated by the broken line, distance pieces being provided between the inner flange and the outer wall where the bolts pass through.

In th upper left hand part of Figure 2 I the arrows indicate the coursev taken by the liquid between the inlet pipe is andthe outlet pipe m. It will be seen that a number of partitions n are provided in the chamber for thepurpose of determining the course taken by the liquid which flows through the core in one direction in a group of three tubes and then returns through in the opposite direction in an adjacent group of three tubes, repeating this until the outlet is reached. The partitions n shown in broken lines are located at the opposite end of the machine to that at which are located those shown in full lines. It will be understood that in order to complete a system of this kind another inlet pipe 76 and outlet m will be provided diametrically opposite to those shown.

In the example illustrated inFigure 2 the tubes 6 of metal are formed in pairs as a narrow U piece and are then inserted in the holes in the core after an insulating lining has been provided as previously indicated, and their ends are then bent over and jointed together by insulatingcouplings as shown in Figure 4. The coupling consists of a sleeve 0 of rubber which is bound by means of wire on each tube end, these ends being slightly splayed so as to provide a lip to ensure security of fixing. It will be seen that the tubes are connected in groups in series, each group connecting at each end with a terminal piece such as p and it will be recognized that it is not essential that an insulating coupling should be inserted between each pair. It will, however, generally be advantageous to utilize such an arrangement of coupling as a joint of some kind is necessary at each of these places.

Instead of placing the tubes in series as in the arrangement just described, they may be connected in parallel, for instance, in the manner shown in Figure 5, a pipe or chamberg being arranged to make the interconnection and having a branch 7 for coupling to each pipe 6. The coupling is made by means of a screwed union 8 between the two parts of which are gripped flanges formed on the tube 6 and tubular piece 1", an insulating washer 2? being inserted between these flanges and an insulatingsleeve it between the tube 6 and one part of the union 8.

Where the lining of the ducts is nonmetallic, it will generally be possible to connect the ducts up at the ends in a manner decided on by the form of circulation to be produced and the positions of adjacent parts since there will be no possibility of producing circulating electric currents by, the action of the flux on the'ducts. here, how-' ever, conductive tubes are employed, it will be seen that only those which are acted upon by flux so that no appreciable diiierence of potential is produced between adjacent ends of the different ducts can be interconnected by metallic members. The tubes, or the groups of equipotential tubes may then either be joined to nonconductive end chambers or to conductive chambers or tubes by means of insulating couplings.

For the cooling fluid, water', oil or other suitable liquid may be employed and may be either passed once only through the system or may be kept in continuous re-circulation passing through a cooler on the. way from the outlet from the system to the inlet.

What I claim as my invention and desire to secure by Letters Patent is 1. In an electric machine, the combination with a core, of a cooling arrangement comprising a circulating system for cooling liquid consisting of longitudinal tubes which run through the core and are separate from the electric conducting winding in the latter, interconnecting hollow parts at the ends of said tubes, said tubes and said parts forming a closed system in the machine, and hollow insulating pieces so inserted in the said system as to prevent the existence of electric conductive continuity therein while maintaining the completeness of the closed passage for liquid through the machine.

2. In an electric machine, the combination with a core of a cooling arrangement comprising a circulating system for cooling liquid consisting of metallic tubes running longitudinally through the core, metallic end connections between said tubes and insulating couplings inserted in the end connec tions so as to break up the electrical conductive continuity in the system.

3. In an electric machine, the combination with a core of a cooling arrangement com prising a circulating system for cooling liquid consisting of metallic U tubes inserted through longitudinal ducts in the core and insulating coupling pieces between the ends of adjacent U tubes.

In testimony whereof I aflix my signature.

GIULIO SOHROEDER. 

